Vacuum distillation



March 1941- K. c. D. HICKMAN VACUUM DISTILLATION Filed Nov. 3, 1939 2 Sheets-Sheet 1 rwvrvm man Kenneth C.D.

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7553:5711 77 a PESIIEIRNAANNAQ" .dllllanlllillilb March 11, 1941. K. c. D. HICKMAN 2,234,166

VACUUI DISTILLATION Filed Nov. 3, 1939 2 Shuts-6116a 2 Fig.3. Y

' ms'nm'rc 0w- DISTILLATE OUT .. RESIDUE OUT 3mm Kenneth C.D. H on Patented Mar. 11, 1941 [I I i v a UNITED STATES. E T O E VACUUM DISTILLATION Kenneth C. D. Hickman, Rochester, N, 1., as-. signor to Distillation Products,.lnc., Rochester, N. Y., acorporation of Delaware Application November 3, 1939, Serial No. 302,747 6 Claims. (01. 202-205) This invention relates to the art of vacuum be achieved in'a single act'of evaporation and distillation and in particular relates to apparatus condensation. In accordance with my invention for high vacuum unobstructedpath distillation the still is provided with a conical vaporizing from moving heated vaporizing surfaces. v surface from which distillation takes place from In application 99,632, filed September 5, 1936, the inside surface thereof." v i I have described vacuum distillation procedure Fig. 2 is a fragmentary enlarged detail of the wherein the substance to be distilled is intropump located at the base of the condensing units duced onto a moving heated surface over which in Fig. 1. g it is caused to pass due. to the movement of the Fig. 3 is a'diagrammatic drawing of a plurality surface at a rate substantially greater than would of multi-stagestill units similar to that illus- 10 be obtained if the distilland were caused to flow trated in Fig. 1 allof which are housed in a single by gravity. One of the methods of distilling in still casing. v I this manner involves introducing the distilland Fig. MS a fragmentary detail of the upper edge onto the approximate center of arotating disk of the conical vaporizing surface and illustrates or plate whichis heated to distillationtemperthe manner in v which" the undistilled residue 15 ature. whichcollects in the turned edgethereof isre- This invention has for its object to provide immoved. H r proved. distillation apparatus of the nature de- Fig. 5 is a fragmentary detailofthelower port-- scribed above. A further object is to provide high tion of the cone vaporizing Surface ,i d 15 vacuum unobstructed path distillationapparatus trates an alternative method of removing con 20 for distilling from a moving surface whereby densate from thelowest portion of'the confractionating may be accomplished from one densing surface. f moving surface. A further object is to provide Fig. 6 is adetail of a modified method of redistillation apparatus whereby distilland can be moving residue from the upper edge'of the cone introduced onto the inner surface of a heated reand illustrates the edge of a conical evaporator 25 volving cup or cone and a plurality of' fractions wh ch is Surro ded by a sta i nary glitter t0 separated from the distilland during its passage collect the undistilled residue. over said surface. A further object is to provide Referring to Figs. 1, 2; and 4, numeral [0 improved high vacuum unobstructed path disdesignates a cylindrical still casing mounted upon tillation apparatus. A still further object is to ba e plate l2 in'a gas-tight manner. The cas 30 provide an efficient centrifugal still which avoids is provided with a'closure [4 to which is conproblems of pumping condensates and residues nected evacuat g c ui 15- At the pp o and/oravoids difficulties due to splashing of disat center of plate l2, there is provided a shaft. tilland or residue during its passage. over the. 8 wh pas s thrOlIg'h a p k alst l n centrifugal surface. Other, objects will become 0- S t I8 is i te al w th a d terminates i 35 apparent from the following description and 00116811941561 vap iz Surfac e shaft 15 claims. rigidly mounted by means of support 24 sothat These and other objects are accomplished by cone 22 is maintained in. the position illustrated my invention which includes apparatus whereby w en ot ted byforce transmitted throu D 1- vacuum fractional distillation, i. e., separation ley 26. The upper'edge ormouth'of 'cone 2! 40 of a plurality of fractions or repeated fractionais bent or turned inwardly o f inverted. tion of a single fractionis accomplished by disgutter 28. Cone 22 vis'surroundedby an electillation from one, heated, cone or cup shaped, trical heating'element '30, the heat from which rotating vaporizing surface. A plurality of such is reflected against the column y reflector 3 multiple effect cone surfaces can be employed. Numeral 34 designates a conduit which intro 45 In the following description I have set forth duces the distilland onto theupper portion of the several of the preferred embodiments of my invaporizing cone at the pointwhere it terminates vention. However, it is to be understood that nee-T t e OH Nu e a 35 d s es a Co they are given for the purpose of illustration and one end of which terminates inside gutter 28 and not in limitation thereof. a which serves to withdraw undistilled residue from 50 In the accompanying drawings. in which like the top of the cone vaporizing surface. I

numbers refer to like parts. Numerals 38, 40, and 42 designate a'plurality Fig. 1 is a vertical section of a still adapted of double-walled condensing surfacesarranged in to repeatedly fractionate a component and sepasequence within the cone 22 but in spaced rela-.

at rate it in a form more concentrated than could tion thereto. Each of thecondencing units It,

1 {tilled residue is removed;

edge. The base of condensing unit "is preferably located so that condensate dropping there- 22 at a point approxiinately opposite to the .low-

est portion of condensing unit 40. The bottom edge of condensing unit 48 is so located that condensate dropping therefrom by gravity strikes the vaporizing cone at a, point a proximately opposite the lowest portion ot condensing unit 42. The pathof the condensateiii dropping from condensing units II .and 42 is shown -in dottedlines. The condensing. units 2!, and 42 are so designed as to leave gaps and (Odor removal j of air and gases from the distilling gap. Numeral designatesa cup integraiwith the bottom portion of condensing unit 42. 'I'hebaseoi thecup is extended downward and withdrawal conduit entirely; located within the extension III-The Ineral 6|] designates a ballvalve at the topof; the pu p.

through which theoriginal distilland 183mm duced-ontothe first-distilling unit A. Numeral m; designates the conduit which removes undistilled residue from vaporizing eolmnn or still A at the' 'upper edgerthereotanddelivers it onto Y B. Numeral .I lanesisoates th conduit. through Y which the that fraction separatedin stillQ'A is {withdrawn r'mn'r the. still; Numeral. Magnesia; 'inates a-conduit which serves to remove the sec londiraction rractionally distilled in stilLB, N'uimeral Y'I 2l-1 designates a conduit' which serves to remove undistilled residue from the; vaporizing iconejoi still B and-delivers it onto the upper portion of. thervaporizing cone in still 10.: "Numeral H22 designates a conduit, through which the trac itio'nal distillate separated in still Q is removed lfirom the apparatus. Numeral 1,I2l desi'gnates, a= fconduit which serves togconveyundistilled resi- 1 fdueriromstill B 'onto the vaporizing cone or still v D..'-' Numeral l2! deslgnates a'conduit by which distillate iractionallyidistilledin still D is re rlmovedifrom the apparatus. IgNumeral I2! desig'i hates'aconduit'which delivers residueundis'tilled instill D onto the cone vaporizingjsuri'aceoi' still E; fiumeral IIII designates a conduit for removing the fraction separated in still Eland numeral 1H2 designates a conduit from the top suriacelof vaporizing cone in "still' E by which flnalfundis from by gravity will strike; the surface of cone III extends into said extensiomr At thebase or, conduit 60 and located intheextension oi cup 48 is a magnetically operated pump 82 which is,

mfl ieticpump construction is shown in Fit. 2 I, and involves a hollow plunger I! provided with Y a ball bulbli which is pulled upwardly by sole gnoid 52 and moved downwardly by gravity.v Nu-v Referring to Fig 3, numeral Ill designates a cylindricalcasingprovided with top and iplates Il2 andqlll. ,The upper or toprplate is. integral with evacuating conduits ,I I. Within the casing] I00 are mountedfi complete r f unit 4,1 C, D, a d E. which "su ta y; 1 [identical with the distilling unitshownin Y Alternatively-thaw. be of progressivelydh the u r mono the va rlzing conewot still.

' ppe p0 I p0 proximately opposite the lowest portionof the i ity as shown into the bottom or vaporizing cone 122') The base of the cone is provided with a flange I52 which extends an appreciable distance from the inside and outside wall of the cone.

pluralityoi holes I54. Numerafiii designates an annular 'gutter into which flange I52 pro- {trudes at its outer edge. Numeral I58 designates al'condul't for withdrawing liquid irom gutter lit in Figs. 1, 2and 4, conduits it are conneciedto'v ja source of high vacuum and the systemds pulley". I Electrical heating-unit I0 Put nto operation so that vaporizing cone 22 is heated to distillation temperature.- Distilland which is the upper portion of cone 22', the illin o'fdistil--' land is heated to distillation temperature; Va: pors thus produced condense on the cooled walls "or condensing unit 38;, Undistilled residue' collee-ts in gutter 28 at the topoi the cone and due-'- Immediately below the flange are provided a I w r 20 .evacuated to the' required, extent; 1Cone' 22 is "caused to rotate by force transmitted through to the speed of rotation is thrown-into the end I of conduit 38 as illustrated in The inertia oi the liquid entering conduit" is sub 'ficient to cause it-to flow up hilltheshort dis; tance required to get'overjthe top :or cone-22. Y This undistilled residue then flows from thfstill or is introducedonto thenext still of the: series if a plurality o fsuch stills are employed." Y

Liquid condensing on the surface 01' condensing unit-38 flows to the base thereof "anddrops by gravity on to the surface of cone as illustrated by the dotted lines. The point of contact between these droppings andthe eone'is preIerabIy ap-Q next lowest condensing unit 40. This condensate dropping onto cone 22 is 'caused' to fiow upwards by centrifugal force. "'I'he'eone'is heatedfand distillation 'from this upwardly flowing film-0t and condensed on unit 38. are substantially rejectedj during this upward travel 'andithese-lowa vapor pressure fractions are immediately inter v 5, I mixed with the fresh distilland as it passes over the upper portion of the-cone, The IIIOXQ'VOlflg tileportions are vaporizedand condense oncon' densingunit '40. r This condensate news by grayity to thebottom edge or and drops onto the v pqrizing'cone at a point appro xirnately oppba site the basejof condensing. unit '42. 'l hese r pings are'likewise caused to flow-upwards in a thin illm and vaporization of the lightest vapor pressure component t'akesplace. Lower vapor pressure components remain undistilied and come intermixed with the droppings from c0ndensing unit '38. q The lightest and substantially pure fraction condenses on-icondensing unit 42,

flows byigravityinto cup land is elevated trom'this point by magnetic pump' Rand-is '.v

25 5 preferably in a degassed condition is introduced Y underthe inside surface of cone"'22by wayo! conduit 34. This distilland is caused to new onward'frornthepoint of introduction to the mouth j v q withdrawn through the still by way choonduit II.

It will be seen that a three-fold fractionation is directly accomplished by the one operation of introducing distilland onto the upper portion of the cone surface, Fractionation then automatically takes place with automatic return of condensate to the appropriate points on the vaporizing surface. No pumps or manual operations are required to effect the separation of a; highly concentrated fraction by this apparatus.

The pitch of the cone can be varied substantialiy in order to permit variation in number of condensing surfaces employed. Also the contours of the cone need not be uniform throughout the length and any cup-shaped vessel may be used. Such variations are to be understood as being within the meaning of the word -cone"' as used herein. Of course the number of condensing surfaces can be variedwidely and in case three successive fractionations are insuflicient to purify a fraction completely,-the length or pitch of the cone can be altered to permit-the useof a larger number of condensing units. Insteadof utilising free gravitationalfallto return mama, ous distiliates to the appropriate portions oi :the vaporizing surface the returncan be, eifected by pipes. gutters or wetted rods. These can b'e at iixed angles other than a the. vertical and; the liquid distillate thus returned to any lower point. This variation permits the arrangement" of the condensingsurfaces to be-varied. For instance. the condensing surfaces can be then located closer to the cone. Also, gravitational return of distillate to the cone is not a necessary feature of my invention. If desired the cone can bearranged upside down and the condensing surfaees provided with collecting gutters. from which the distillates could be pumped through return pipes to appropriate higher portions of the cone.

In some .cases'the removal of the flnal distillate fraction by the method illustrated in Fig. 1 is inconvenient. Many other methodsare available. The flnal fraction can be frozen and mechanically removed continuously or intermittently. lndless conveyor belts may be used to-remove I either in liquid or solid form. Rod operated piston or gear pump mayreplace the magnetic pump. An

alternative method of removal is illustrated in Fig. 5 during the "operation of which condensate drops from condensing surface 42 into the lower portion of the cone 2!. Due tocentriftigsl force,

this liquid condensate is lifted as far as flange I52. However, instead of overflowing the inner edge thereof it is forced or flung through holes I" into gutter I". Any liquid which tends to travel from holes Ill up the outside surface of.

cone 2! is stopped by the outer edge of II and is flung by centrifugal force into gutter Ill. The condensate collected in gutter III is removed from the still by way of conduit! it.

when operating apparatus provided with the gutter removal means shown in Fig. 6, the undistiiled residue is thrown by centrifugal force from outwardly. turned edge III, This residue is caught by gutter I and flows into conduit Ill through which it is removed from the still.

The operation of each of the units illustrated in the apparatus of Fig. 3 is substantialiy' thesame as that described in connection with Fig. i. In each unit the substance to be distilled is introduced onto the upper portion of the vaporising coneand distillate thus obtained is thrice fractionated and the flnal fraction removed.

throughcondaits I, III, I, III and la.- The "could be more clearly seen.

lowest fractionis removedin concentrated form in still A. Thenext highest'boiling pointfraction is removed in still B, the next highest in still C. etc. The number ofstills should correspond to the number of fractions which are to be separated. The apparatus illustrated in Fig. 1 could be used in series, each unit of the series being housed in a separate casing, However, disposing all of the still vunits in a single casing greatly reducespumping costs and other operating expauses and dimculties.

The vaporizing cone can be divided into a plurality of definite temperature zones. The passage of undistilled residue from-one to the other of which can be easily accomplished without splashing by numerous devices. one of which is slight oven-lapping of the different zones. Ordinarily i prefer to employ asinglevaporizing cone and, if need be, heat the-different vaporizing zones thereof to diiferentvaporizing temperatures. The condensing zones likewise can be constructed asone continuous surface. At appropriatepoints flanges or similar drop-oi! leavesmay be providedfto direct downwardiyiiowingl condensate from the condensing surface'so that it will drop onto the vaporizing coneatthe appropriate point. I prefer to use separate ,vaporizing units since the gapsbetween each unit. such as gaps and 46, Fig. 1, provided additional .space for removal off'gas'erfrom' the distilling zone.v If-desired evacuating pumps can be directly connected to the top edges of each such con-' densing unit. Very efiicient, removalof gases :wouldthen be possible. The conical surface has the decided advantage that direct'introduction of liquid thereon at a plurality of points does not cause splashing.. The introduced liquid is 1 thrown against the conical surface and held tightly thereto. v i The vapors derived from the diiferentlvaporizing surfaces or zones may become mixed to a certain extent. The mixing diminishes as the distance between thecondensing and vaporizing zones is shortened. With a four foot cone and a distance of' two inches mixing is not serious.

The distance shown in the drawingsare rather large in proportion to the. plates. and were made artificially wide so that the details of construction The mode of recirculation to accomplish emcient fractionation can bevaried greatly; Y Thus the distilland may be introduced onto the intermediate vaporizing areas of the cone instead of on the lower or upper segment. Condensate from i 1 the diflerent condensing zones maybe recirculated in a variety of sequences to improve fractionation or to accomplish aparticular fractionatingrresult. Attention is directedto U. 8. Patents 2,073,202 and 2,128,223 for common 7 methods of recirculation whichmay be used with but the rate of distillation varies with the area exposed and the molecular weight. as well as with the temperature.- If the area is increased the same result is obtained as if the temperature were, -increased, buts the area maintained -the same .orreducedi Thearea of, coursezcontrols the 1 time ofiheatin'g or the distilland which 1 also "'afictedby me ped rotation.v Therefore, the

difierentyzones can. have] equalarea's and be r; heatedto successively higher temperatures or they they be: heja'gtedTito equal temperatures with *eecrea'sm area or anrombi cti 0 W 5,1 ,[Incrdervito separate a larg r m r ffra -c l0 'tions ithanTthos'e specifically described, any of the difie'rent forms of apparatus maylbe employed in combination by.connecting'".them in 's eries The temperature'or(temperatures in each unitpi the 4 1 ;'series ,will be appropriate for thecmnponent recr'ease from oneunit t'o'the other in the same eorderfthatthe distilland passes therethrough. l i 1. n cni a p i a to g ,"vacuu1n distillation conditions. However; I have ",foundi' it to beof particularvalue for distilling f movedg th ereinand "will usually progressively inunder/high vacuum 'unobs'tructed path distilla tionconditions; i.- e. at pressures of below ll mm.

j' such as for instance ;1.-.00 1.Ym1n. and with lconl 'mouthoi' the cone vaporizing surface, means for lconveyingcondensate from each ofthe condens ing surfaces vor zon'esex'cept the last, onto 'the" 1 v densing and vaporizing surfaces s epa'ratedsby sub-- stantially unobstructed. jspace. Whenjthe ,dis-j tance between the surfaces is short such'asja disv I 7 tance less than 12', and] preferably a distance of bou /2 o 6,the" distillation is known as high hz 'i ii l t nsz- Reference is ma'deto mygapplication No. 99,632 referredto abcveforfurther vdetails ofj c'on'structionvof stills ,havingmoving surfaces, their mode r r v of operation and materials operatedlupon.i..In tatable cone is approximatelyyerticalf'with, the mice-filed application Serial; No..'302,7&$. filed f Novemberfi, 1939, I havedescribed otherforrm' of fractionating centrifugal fractionating surfaces -andrreferencesis made thereto forfurther detailjs of ccnstruction andoperation of centrifugal stills.

What'Iclaim is;,, r

7, ;1-.* High vacuum, unobstructed path fractional I distillation apparatuswhichcomprises incom- 45Qbination; a rotatable cone shaped vaporizirigsur- 5. face, aff plurality of condensing zones arranged within the gconel and separated therefrom by, Substantiallyr-t unobstructed space, a conduit for in troducing liquid to be distilled'onto the insjide of thevaporizing cone so that during operation it is caused toflow thereoverjhy centrifugal force tor {ward the mouth thereof, means for removing unqdistilled residue from'the mouth of th'evaporiz ingsurface, means for separately removing con within the cone and separated therefrom byfsuii- .stantially unobstructed space, a conduit forinv troducing liquid to be distilled onto the insideof v the vaporizing surface near to the mouth thereof,

rso thatjduringoperationit iscaused to flow-thereover toward tlie' moutn by centrifugal force,

, a a ea distillation under means forremoving undistilled residue from the moutfi'of the vaporizing surfacefme'ans for re-'1 turningcondensate from each of the condensing condensing and vaporizi Surfaces; t and means forremoving from the still condensate which Iconnscs' onthev last condensingsi irfa e 'bfi'th Vacuum, b t u e path fractionat distillation apparatus which comprises" in combination a rotatable coneshaped vaporizing surface, a series of condensing'surfaces or zones'ari ranged. in sequenceiwithin'the cone but in spaced relation with the walls thereof, means for heat-* "'ing the cone surface;'means for cooling the condensingl surfaces, a conduitforjintroducing liquid r 1 .0 be distilled onto .the insideof. the vaporizing. 20 "to" flow thereovjerfrom the point of introduction 1 to "the niouthjof the conevaporizing s'ui'face;

cone surface so that during foperationit is caused means for removing undistilledresidue from the vaporizing cone at a point approximately oppo- 7 e site to the portionof theneigt condensing" surface I vacuu 'sh rtvpathflistillation. When the dis-" tanceis less than thenieajn free path it is known a molecular. sMy-finvention is Iapplicabie to, all

or zone in the series, means-for "removing cone pace between: the condensing sur'fa'cesfor zones andj'the vaporizingcone,

4.- ITheQappaIatusbf claim 3' it which theromouth of the cone uppermost.

,s'ur'facesexcept the-last, to the cone'ata point farther'from the mouth than it was vaporized- 5."Ihe apparatus of claim} in" the rotatahlefloone j'is approximately vertical and the condensin'gs'urfaces or zones are arranged 'so'that I the vreturn of condensate to the cone takes place bygravitationa1 force; i

, 6. High vacuum unobstructed path fractional distillation apparatus which 'co'mprises"in com- .bination arotatablel, cone shaped. vaporizing jsurfao'epa series of: condensing surfaces or zones ,ar-

ranged in sequence within the cone but in spaced relation with the walls thereof means for heating the cone surface, means for cooling the condening/surfaces, a conduit forfint'roducing' liquid to ,be' 'di stilled onto-t the" insidef'upper portion of; the

vaporizing cone surface so thatduring operation it is caused to flow thereoverin' an upward direci I nonfi m the point of introduction to the top of 'densa'te from each of 'the condensing zones and means for. evacuating the spacebetween the con-' giensing zones and the vaporizing surface,

12. High vacuum, unobstructed path fractional Y J the cone vaporizing. surface; means" for removing undistilled residue from the top of. the vaporizing ,.suriace',meanss fon'conveying condensate from each of the condensing surfaces or zones exc'ept 3 the lowest ontothe vaporizingconefat a point apif proximately opposite to the lowest portionfloi the nextlo'west condensing surface or zone in 'the series, means for removing condensate from: the 1 still/which collects onthelowest condensing sur- I y face or"zone and means for maintaining a high Fvacuum I in the space between the? condensing surfaces orzonesandfthe vaporizing cone;

D-- HICKMAN- 

